#3 basename for the logfile

[Stefan Sauer]

It wound be nice to specify a basename for the logfile
(--log-file).
When running several apps under refdbg (e.g. run all
unit tests) the log is overwritten each time.

So it would be nice, if I could say
refdb --log-file=/tmp/myapp.refdbg ./myapp
and it will log to the given file-name.